The present invention relates to an apparatus for driving an intra-aorta balloon pump which is designed to expand and contract the intra-aorta balloon pump by alternately supplying positive and negative pressures thereto.
In general, it is preferable that the volume of the expansion of an intra-aorta balloon pump should be changed in accordance with the degree of recovery of the living heart. In order to meet with this requirement, an improved device has been provided which is shown in U.S. Pat. No. 4,796,606 for example. In this device, the expansion of intra-aorta balloon pump can be changed on the basis of a difference between the pressure in the balloon pump and the blood pressure of the patient.
However, in this conventional device, once the expansion of the intra-aorta balloon pump has been changed, the resulting expansion can't be changed furthermore so long as the device is in operation. In other words, while the device is running, the pressure change in or the expansion degree of the intra-aorta balloon pump is constant. Thus, it is difficult to establish a precise change of the expansion degree of the intra-aorta balloon pump in accordance with the recovery of the patient.